BoilerFaultCodesYour boiler is performing a routine cooling cycle to clear internal gases after a burst of activity and is not currently in a fault state.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: fan overrun
What causes this fault?
This occurs when the boiler’s fan continues to run after the burner has switched off to safely purge remaining heat and combustion gases from the unit. It is a normal safety process that typically happens after a period of intense heating or hot water demand to ensure the internal components cool down correctly. Your boiler hasn't broken down; it is simply finishing its work cycle before it can start again.
DIY fix possible
Wait for 5-10 minutes to allow the cooling cycle to completeEnsure your thermostat is not calling for heat if you want the fan to stop soonerCheck that the boiler display changes to a different code after the cooling period
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like S.16 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Ultrapower sxi is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.